Developing on Replicant isn't much harder than developing on any other free software project as it doesn't require specific knowledge. In fact, you'll probably learn a lot along the way regarding how hardware works, how the Android system is composed, how the kernel works, etc, but you don't need to know all of this to start. However a basic set of skills is required, among which:

C language programming skills and the ability to understand other languages such as C++ and Java

Makefile skills (no need to know every detail about it, a general idea of how Makefiles work is enough)

Git skills (basically, how to commit changes, send them to our repos, dealing with branches without making a mess, etc) You can find some documentation about Git at: https://git-scm.com/documentation

If you think you can cope with the requirements, then developing on Replicant should cause you no particular issue.

The porting guides provide instructions for porting a new device to Replicant and also offer some tips for developing on Replicant.

Have a look at the Tasks page and feel free to ask around for help to get started.

Writing free software replacements for non-free components may require more skills depending on what you're trying to achieve, though there may be people with the adequate knowledge to help you and from whom you will likely learn a lot.

Replicant's source code is hosted at git.replicant.us. If you plan to regularly contribute to Replicant and if you don't yet have a code hosting provider that satisfies your needs, you are welcome to host your Replicant-related projects there under your own username, You only need to contact one of Replicant's developers and ask for an account. Please include in your request the name, username and Email address that should be used for creating your account. Your repos will then show up on the contributor repos page.

Replicant currently doesn't accept merge requests. There are two ways to get your patches included: You can either send them to the mailing list or open an issue on the issue tracker and attach the patches to the issue. Replicant developers will then review your changes.

See the Git documentation for creating a patch. Patches can be send with git send-email. If it's too much hassle for you to set up git send-email, sending the patches with your favorite mail client should be fine, too.

Here are some tips that may help you achieving a free software replacement for a specific component (some may be more or less relevant regarding the nature of what the component does):

Look for interested people from other projects: LineageOS people are constantly fighting with non-free blobs and are sometimes happy to help replacing one.

Use tools such as strings, objdump and radare2 against the non-free binary to have a better idea of how things work. (Make sure this is legal where you live!)

Try to make the non-free binary as verbose as possible by enabling all the possible debug options on the config file or such.

Run the program in strace and analyze the trace to understand what the program does.

Add verbose debug prints in the concerned kernel driver (with printk and show them via the dmesg tool).

Read the corresponding kernel driver: you can sometimes learn a lot by reading comments or headers.

Collect data out of the kernel driver (via debug prints) and out of the non-free binary (via debug prints on the upper-layer).

If there is a mathematical algorithm involved, force the values returned by the kernel to the non-free binary and analyze how it reacts, for instance with spreadsheet software.

If you're directly dealing with a hardware component, try to find a datasheet for the chip, it may hold precious details. In the best case, you may also be able to find a reference software implementation!

It is generally a good idea to send some changes back to upstream, assuming that they will benefit from it as well.

When it is about the replacement of a non-free component present in the upstream systems, make sure that your replacement is reliable and complete.Contact the interested developers on the upstream projects before attempting to send your replacement.

When working with Replicant repos, make sure to avoid breaking things. For instance, if you push a commit introducing a compilation error, it will break the whole build process.It is better to create separate branches (that are not used by the official manifest branches) when your work is still in progress.Creating branches that add debug infos on a particular topic is usually a good idea since it will save you time next time you want to debug the same component.

LineageMirror details the setup of the LineageOS mirror. Below are the instructions for repos in the Replicant group.

In order to keep repo naming consistent, please name repositories by their name on the tree, replacing the / by _.For instance, when forking the LineageOS repo: android_device_samsung_crespo, rename it to device_samsung_crespo on the Replicant repos.This creates a more consistent way of naming repositories and makes it easier when pushing: just look at the location in the source tree and replace / by _.

Such as: replicant-2.3 This should be used on the projects repositories as well as the manifest repository.Any other branch should be considered as Work In Progress (WIP) and thus not be part of any official branch of the manifest.

There is although one exception, with the master branch, that can be used by any project and be in any manifest given that the code held in the master branch will work on any Replicant version.

1. Create the device main page, following the naming guidelines applied to other devices (e.g. the Samsung Galaxy S II GT-I9100 is called Galaxy S 2 (I9100) and its page is GalaxyS2I9100)2. Create all the related sub-pages (build guide, install guide and firmwares list at least), following the naming guidelines applied to other devices (e.g. GalaxyS2I9100Build, GalaxyS2I9100Installation and GalaxyS2I9100LoadedFirmwares)3. Link the sub-pages to the main page in the index4. Update the ReplicantStatus page of the wiki with the current status of the device5. Modify the Index page of the wiki and add the new device in the following sections: